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Background: In the recent past, we have synthesized and reported different derivatives of oxadiazoles as potential α-glucosidase inhibitors, keeping in mind, the pharmacological aspects of oxadiazole moiety and in continuation of our ongoing research on the chemistry and bioactivity of new heterocyclic compounds. Methods: 1,3,4-Oxadiazole derivatives (1-14) have been synthesized and characterized by different spectroscopic techniques such as 1H-, 13C-NMR and HREI-MS. Result: The synthetic derivatives were screened for α-glucosidase inhibitory potential. All compounds exhibited good inhibitory activity with IC50 values ranging between 0.80 ± 0.1 to 45.1 ± 1.7 μM in comparison with the standard acarbose having IC50 value 38.45 ± 0.80 μM. Conclusion: Thirteen compounds 1-6 and 8-14 showed potential inhibitory activity as compared to the standard acarbose having IC50 value 38.45 ± 0.80 μM, however, only one compound 7 (IC50 = 45.1 ± 1.7 μM) was found to be less active. Compound 14 (IC50 = 0.80 ± 0.1 μM) showed promising inhibitory activity among all synthetic derivatives. Molecular docking studies were also conducted for the active compounds to understand the ligand-enzyme binding interactions.

Oxindole derivatives 3-25 have been synthesized from commercially available oxindole by refluxing with different aromatic aldehydes in good yields. Their in vitro antiglycation potential has been evaluated. They showed a varying degree of antiglycation activity with IC50 values ranging between 150.4 - 856.7 µM. 3-[(3-Chlorophenyl)methylidene]- 1,3-dihydro-2H-indol-2-one (IC50 = 150.4 ± 2.5 µM) is the most active compound among the series, better than the standard rutin with an IC50 value 294.5 ± 1.50 µM. The structures of the compounds were elucidated by 1H-NMR and mass spectroscopy and elemental analysis. A limited structure-activity relationship has been developed.

Benzophenonehydrazone Schiff bases 1-25 were synthesized and their in vitro antiglycation potential has been studied. Out of twenty-five compounds, thirteen showed varying degrees of antiglycation activity with IC 50 values ranging between 25.7 - 305 μM, if compared with the standard rutin (IC 50 = 70.5 ± 0.50 μM). Compounds 21 (2,3- dihydroxybenzaldehyde N-(diphenylmethylene)hydrazine) IC 50 = 25.7 ± 0.003 μM, 14 (diphenylmethanone N-[1-(2,4- dihydroxy-5-nitrophenyl)ethylidene]hydrazine) IC 50 = 36.6 ± 0.004 μM, 6 (3,4-dihydroxybenzaldehyde N- (diphenylmethylene)hydrazine) IC 50 = 49.5 ± 0.001 μM, 13 (diphenylmethanone N-[1-(2,5-dihydroxyphenyl)ethylidene] hydrazine) IC 50 = 52.6 ± 0.023 μM, and 15 (diphenylmethanone N-[1-(3,4-dihydroxyphenyl)ethylidene]hydrazine) IC 50 = 57 ± 0.002 μM, showed showed much better antiglycation potential superior to the standard rutin. The compounds 7 (2,5- dihydroxybenzaldehyde N-(diphenylmethylene)hydrazine) IC 50 = 66 ± 0.002 μM, and 25 (diphenylmethanone N-[1-(2,5- dihydroxyphenyl)propylidene] hydrazine) IC 50 = 67.9 ± 0.001 μM showed compareably good antiglycation activity to standard rutin. All compounds were characterized by spectroscopic techniques and gave satisfactory elemental analysis.

Syntheses of thirty 2,4,6-trichlorophenylhydrazine Schiff bases 1-30 were carried out and evaluated for their in vitro DPPH radical and super oxide anion scavenging activities. Compounds 1-30 have shown a varying degree of DPPH radical scavenging activity and their IC50 values range between 4.05-369.30 µM. The compounds 17, 28, 18, 14, 8, 15, 12, 2, 29, and 7 exhibited IC50 values ranging between 4.05±0.06-24.42±0.86 µM which are superior to standard n-propylgallate (IC50=30.12±0.27 µM). Selected compounds have shown a varying degree of superoxide anion radical scavenger activity and their IC50 values range between 91.23-406.90 µM. The compounds 28, 8, 17, 15, and 14, showed IC50 values between 91.23±1.2-105.31±2.29 µM which are superior to standard n-propylgallate (IC50=106.34±1.6 µM).

Acylhydrazide Schiff bases 1-27 were evaluated for their in vitro DPPH radical and superoxide anion scavenging activity. They showed a varying degree of DPPH radical scavenging activity with IC(50) values between 31.25-473.59 µM. Compounds 8, 2, and 10 have IC(50) values 31.25 ± 1.32, 34.40 ± 0.66, and 37.24 ± 0.4 µM, respectively. Standard npropylgallate showed an IC(50) value 30.12 ± 0.27 µM. Acylhydrazides 1-27 exhibited in vitro superoxide anion scavenging activities with IC(50) values in the range of 175.6-450.89 µM. Results demonstrated that acylhyrazides 8, 2, and 10 have DPPH scavenging activity, comparable to standard n-propyl gallate while acylhyrazides 1-27 were found to be less superoxide anion scavenging active than the standard n-propyl gallate (IC(50) = 106.34 ± 1.6 µM).

2,4,6-Trichlorophenyl hydrazones 1-35 were synthesized and their in vitro antiglycation potential was evaluated. Compounds 14 (IC50 = 27.2 ± 0.00 μM), and 18 (IC50 = 55.7 ± 0.00 μM) showed an excellent activity against glycation of protein, better than the standard (rutin, IC50 = 70 ± 0.50 μM). This study thus identified a novel series of antiglycation agents. A structure-activity relationship has been studied, and all the compounds were characterized by spectroscopic techniques.

Disulfides 1-30 have been synthesized and their in vitro leishmanicidal activity has been evaluated. Compounds 18 (IC50 = 2.70 ± 0.044 μM), 19 (IC50 = 2.85 ± 0.02 μM), 20 (IC50 = 2.92 ± 0.01 μM), 26 (IC50 = 3.69 ± 0.01 μM), 21 (IC50 = 4.45 ± 0.029 μM), and 29 (IC50 = 4.46 ± 0.025 μM) showed a remarkable leishmanicidal activity if compared with standard pentamidine (IC50 = 5.09 ± 0.04 μM). This study has discovered a series of possible molecules as antileishmanial agents. A structure-activity relationship study has also been carried out. The structures of all the synthesized compounds were identified by using spectroscopic techniques, including 1H-NMR and EI MS.